Objectives: Evaluate current resistance trends in Streptococcus pneumoniae (SP) (including efflux) from CAP patients towards the main antibiotics registered for this indication.

Methods: 142 SP isolated in 4 major teaching hospitals over the last 3 years from patients admitted from the community and with CAP diagnosis confirmed by retrospective analysis of medical records. MIC determined by microdilution in CAMH broth + 2.5% horse blood. Susceptibility assessed according to EUCAST and CLSI bkpts.

Results: Based on CLSI bkpt, 99.3% of isolates remained susceptible to AMX, but MIC90 values are elevated. Non-susceptibility to CFX and CRO was observed in about 15% and 10% of isolates, respectively, whatever the bkpt considered. More than 34% of isolates were resistant to CLR, among which 20% [7% of the collection] remained susceptible to clindamycin (denoting efflux). 7% of isolates could be categorised as TEL-I or -R using EUCAST bkpts but only 1.4% would appear as TEL-I according to CLSI. MICs of LVX were higher than those of MXF, but non-susceptibility to both drugs remained low (due to higher LVX bkpts). Reserpine had only a modest effect (0.7% remaining LVX-R according to EUCAST, no change for MXF).

Conclusion: The data show a marked decreased susceptibility of SP to cephalosporins, and a high prevalence of MLSB resistance. Resistance to TEL and quinolones remains negligible based on CLSI breakpoints, but become noticeable for TEL if using EUCAST proposed bkpt. LVX MICs are clearly increased. Efflux significantly impacts on macrolide susceptibility but does not markedly affect LVX or MXF. The data (i) underline the risk of empirical treatment of CAP with cephalosporins and macrolides, (ii) justify the high dose approach with AMX; and (iii) illustrate the importance of setting appropriate bkpts.

Session Details

Date:

19/04/2008

Time:

00:00-00:00

Session name:

18th European Congress of Clinical Microbiology and Infectious Diseases